<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <link rel="stylesheet" href="style.css" type="text/css">
    </head>
    <body>
        <div class="layout">
            <input type="text" id="num1"> + <input type="text" id="num2"> = <input type="text" id="sum">
            <input type="button" value="运算" onclick="getSum()">
        </div>
        <script src="calc.js" type="text/javascript"></script>
    </body>
</html>